The present invention relates to a method for selecting the most effective arthropod repellent from stereoisomers of a compound, involving testing each stereoisomer of the compound for its effectiveness as an arthropod repellent against an arthropod of a particular genus and species, comparing the test results and selecting the most effective arthropod repellent stereoisomer from the stereoisomers of the compound, wherein the compound is a piperidine analog of the formula 
in which R2, R3, R4, R5 and R6 may be the same or different and represent hydrogen, methyl, ethyl, isopropyl, or butyl groups, wherein said methyl, ethyl, isopropyl, or butyl groups are optionally substituted in their primary or secondary position with a hydroxyl (xe2x80x94OH) group, and R1 represents unbranched or branched C1-8 alkanes, unbranched or branched C1-8 alkenes, C5-8 cycloalkanes, C5-8 cycloalkenes, methyl substituted C5-8 cycloalkanes, or methyl substituted C5-8 cycloalkenes or R1 is xe2x80x94Oxe2x80x94R7 wherein a carbon atom of R7 is attached to the O of xe2x80x94Oxe2x80x94R7 and wherein R7 represents unbranched C1-8 alkanes, branched C1-8 alkanes, unbranched C1-8 alkenes, branched C1-8 alkenes, C5-8 cycloalkanes, C5-8 cycloalkenes, methyl substituted C5-8 cycloalkanes, or methyl substituted C5-8 cycloalkenes, and wherein said compound has at least one asymmetric center. Generally, the compound has one or two asymmetric centers.
The present invention also relates to a composition for repelling arthropods, containing a carrier material and an arthropod repelling effective amount of a stereoisomer of a compound selected by the above method.
In addition, the present invention also relates to a method for repelling arthropods from an object (e.g., mammals such as humans) or area (e.g., a surface such as human skin), involving treating the object or area with the above composition.
Racemic 1-(3-cyclohexen-1-ylcarbonyl)-2-methylpiperidine was first identified as an insect repellent twenty-two years ago (McGovern, T. P., et al., Mosq. News, 38: 346-349 (1978)). The U.S. Department of Agriculture assigned the compound a code number, AI3-37220, hereafter referred to as 220 (FIG. 1). The so-called repellent does not necessarily reduce the number of blood-sucking arthropods visiting a site where the compound has been applied, but it does reduce the number of bites sustained by an individual whose skin has been treated topically with the compound; the term repellent is used herein in this context. Field and laboratory studies against many species of blood-sucking arthropods have consistently shown that 220 is more or as effective as the commonly used arthropod repellent deet (N,N-diethyl-3-methyltoluamide) in reducing bites (Robert, L. L., et al., J. Med. Entomol., 29: 267-272 (1992); Coleman, R. E., et al., J. Med. Entomol., 30(3): 499-502 (1993); Walker, T. W., et al., J. Am. Mosq. Control. Assoc., 12: 172-176 (1996); Frances, S. P., et al., J. Med. Entomol. 33, 511-515 (1996); Frances, S. P., et al., J. Am. Entomol., 35(5): 690-693 (1998)).
Compound 220 contains two asymmetric centers and standard symmetric synthesis yields a equal mixture of four stereoisomers. All previous repellent studies were conducted using the stereoisomeric mixture (racemate). Up to now, the repellent properties of the individual stereoisomers of 220 or of other known repellents were never evaluated. The present study determined if chirality plays a role in repellents (e.g., 220).
A method is disclosed for selecting the most effective arthropod repellent from stereoisomers of a compound, involving testing each stereoisomer of the compound for its effectiveness as an arthropod repellent against an arthropod of a particular genus and species, comparing the test results and selecting the most effective arthropod repellent stereoisomer from the stereoisomers of the compound, wherein the compound is a piperidine analog of the formula 
in which R2, R3, R4, R5 and R6 may be the same or different and represent hydrogen, methyl, ethyl, isopropyl, or butyl groups, wherein said methyl, ethyl, isopropyl, or butyl groups are optionally substituted in their primary or secondary position with a hydroxyl (xe2x80x94OH) group, and R1 represents unbranched or branched C1-8 alkanes, unbranched or branched C1-8 alkenes, C5-8 cycloalkanes, C5-8 cycloalkenes, methyl substituted C5-8 cycloalkanes, or methyl substituted C5-8 cycloalkenes or R1 is xe2x80x94Oxe2x80x94R7 wherein a carbon atom of R7 is attached to the O of xe2x80x94Oxe2x80x94R7 and wherein R7 represents unbranched C1-8 alkanes, branched C1-8 alkanes, unbranched C1-8 alkenes, branched C1-8 alkenes, C5-8 cycloalkanes, C5-8 cycloalkenes, methyl substituted C5-8 cycloalkanes, or methyl substituted C5-8 cycloalkenes, and wherein said compound has at least one asymmetric center. Generally, the compound has one or two asymmetric centers.
A composition is disclosed for repelling arthropods, containing a carrier material and an arthropod repelling effective amount of a stereoisomer of a compound selected by the above method.
A method is also disclosed for repelling arthropods from mammals, involving treating the mammal with the above composition.